Cartridge-casing.



WILLIAM H. BUELL, OF NEW HAVEN, CONNECTICUT, ASSIGNOR TO WINCHESTERBEPEATING ARMS COMPANY, OF NEW HAVEN, CONNECTICUT, A CORPORATION OFCONNECTICUT.

CARTRIDGE-CASING.

aoaeae.

E Drawing.

and cartridge cases of both the rim fire and the center fire type.

It is well known to those skilled in the art, that center fireammunition is today made by first forming a cup from a sheet of metaland subsequently drawing it by successive drawing to the desired shape.The metal in the head of the shell is formed to the proper vided with anintendation for the purpose of receiving the primer. 4

Rim fireammunition is of the 'so-called' folded type. The head of theshell is provided with a circular cavity or recess; in other words it isformed into an outwardly projecting annular, hollow rim. This circularcavity or hollow annular rim is for the Heretofore, according to thedevelopment of the art,.it has been necessary in the case of rim fireammunition to provide a, cartridge made of brass containing the 1mm- 85production of sufficient stifi'ness, wherever priming mixturescontaining fulminate of mercury or mercury in any form was to be used.This is for the reason that amalgams are formed between most metals andmercury and with especial ease in the case of zinc alloys so that if amercury priming mixture was placed in contact in a slightly moistcondition with brass containing an appreciable amount of zinc, therewould be amalgamation and the cartridge case. The amount of amalgamationand the degree to which the amalgamation is eflective in weakening thecartridge metal is entirely a matter ofdegree dependent upon the amountof zinc in the alloy, the amount of mercury in the mixture, thecondition of the surface of the metal and the temperature and humidityof the 55 place in which the shells are stored. Where Specification ofLetters Patent.

shape and thickness and propurpose of. receiving the priming compound.

mum amount of zinc consistent with the consequent weakening of- PatentedNov. 21, 1916.

Application filed April 8, 1915. Serial No. 20,087.

a priming mixture containing no mercury has been used it has been shownthat a car tridge case for rim fire ammunition may be made from a brassvery rich in zinc. I am aware that attempts have been made to overcomethe difliculty of amalgamation in rim, fire ammunition so that a mercuryprimer could be used by inserting various linings both metallic andnon-metallic and by various shellacs.

In the case of center fire ammunition the prlming compound is loadedinto a separate primer which may be of brass, high or low in zinc as thecase may be, and which primer is in turn inserted into the primer pocketof the cartridge shell so that in the cases where mercuric primers areused, there is no contact of the mercury of the primer with the shellduring storage. However, when the cartridge is fired, the mercury leftamalgamates with the brass of the shell and the shell will not standreloading. We have, consequently, the same condition of amalgamation ina brass center fire cartridge as in a rim fire, the extent being merelya matter of degree dependent on the method of manufacture andsubsequenthandling.

I have discovered that, by the use of a suitable ferrous metal, I amenabled to make satisfactory rim fire and center fire cartridges andprimers and that I am thus able I to use interchangeably in such casingeither' a mercuric or non-mercuric priming compound. As it is sometimesdesirable for purposes of differentiating in the ignition of a powder touse a non-mercuric primer, I therefore secure the advantage that withoutpreviously selecting the shells or carrying shells made from variouskinds of metal in stock I am able to prime with either a nonmercuric ormercuric compound according to the requirements of the matter.

.I am aware that it has been desirable to make shells from ferrousmetals on account of cheapness over copper alloys but there have beenserious objections inherent with ferrous metals or alloys, 1st:-thatunless specially treated they become oxidized or rusted or otherwisedeteriorated due to at mospheric conditions; 2nd that' there have beencertain difficulties in drawing the shells which have been serious anddifficult to overcome.

- Due to the presence of phosphorus, sulfur,

manganese, and carbon (approximately 1% or over) the metal becomeshardenedin the operation of drawing or forming the shell andconsiderable and frequent annealing is required to prevent tearin thestock. The annealing is also compllcated especially when appreciablepercentages of carbon are present as under such conditions thetemperature of annealing and the rate of cooling affect the final temperof the metal and they must be carefully controlled or otherwise evenafter drawing, the finished shell may be in a hard and brittlecondition. On account of these conditions it has never been possible tosuccessfully make and market an iron or steel cartridge. To prevent rustit was impossible to resort to the usual expedient of galvanizing in thecase of a primer, or a rim fire or center fire shell because if amercury mixture were used the zinc coating would be destroyed; and toobviate the necessity of frequent and careful anneals it was necessaryto secure properties in the iron or steel not possessed by the brands onthe market. Moreover the question of rusting was serious because, if theusual method of galvanizing was employed for protecting the surface ofthe shell, a fulminate primer could not be used, the marked aflinity ofzinc for mercury being so great that in the presence of mercury the zincwould practically wash off and leave the iron eXposed.

The ferrous metal which I have found to be suitable for cartridgecasings consists of nearly pure iron; several brands of steel now uponthe market as regular articles of commerce and consisting ofapproximately 99.95% iron or over can be successfully employed. Ondrawing to form the shell the metal will not harden to a very markeddegree and consequently requires less annealing and less care incontrolling the rate of cooling than was required in the cases where alarger percentage of carbon was present. It may be stated in fact that Ihave found that such an alloy consisting of almost pure iron approachesvery nearly'to having the properties of copper and brass as far aselongation, elastic limit and behavior on annealing is concerned, and Ihave also found that shells made from such an ironare slower to showeffects from rust and can be used with or without a mercuric primingcharge, as described. Accordingly when I refer in the appended claims toferrous metal, I mean to define a steel or iron which has the propertiesand characteristics indicated.

I have further found that by coating as by an electrolytic process or inany othersuitable manner, the whole surface of the metal or that partthereof which would come into contact with the priming mixture, withzinc or its equivalent and in turn similarly coating the zinc withcopper or any other metal not readily attacked by mercury, a cartridgecasing is produced which has special qualities as to resistingrustingwitnesses.

WILLIAM H. BUELL.

Witnesses:

DANIEL I-I. VEADER, JOHN MCLEAN.

